R: "If I understand well, there is no firm ground on which we can accept beyond any doubt that the Khufu-shafts were oriented to Orion ?"
"beyond any doubt" ???????? no one is defining pi here!
So you are yet another one seeking absolute proofs and certainties - are you not aware that we are dealing with a 4600 year old ruin? - AFAIK, the AE did not leave us their building construction manual, or the design criteria / specifications for their creations, so at best its all informed speculation - not the absolute proofs that you demand.
R: "Imo, many people LIKE to think that the AE were capable to orient the Khufu-shafts meticulously, despite the sight-blocking barrier in the form of the immense mass of stones of the pyramid."
That's ridiculous - the shafts are not observation tubes - and its perfectly possible to build them with a predetermined angle of incline obtained from sighting to a star - there is no need to sight through the shafts.
R: "I admit it sounds nice, but, at this moment, there is nothing that points to such orientation."
Of course there is - you can choose to ignore the evidence if it interfere's with your own pet theories, but you cannot change it.
R: "Imo, the shafts were created fo function as exit and enter corridors for the pharaoh's soul (the essence of the resurrection-machine), nothing more, nothing less."
"In 1924, the Belgian Egyptologist, Jean Capart, suggested another purpose for the shafts: "they are often called air-shafts; it is more probable that they had a funerary purpose, perhaps to afford a passage to the soul of the king"
Egyptologist and architect, Alexander Badawy, adopted Capart's idea and enlarged upon it, linking the upper shafts with the circumpolar stars and the Orion constellation:"In the North and South walls (of the burial chamber) are the apertures, similar to those of the middle chamber, of channels square in section, cut out of one stone and roofed with a slab. They are sloping upwards to reach the North and South faces of the pyramid, at the same level and have accordingly different gradients: 31 degs for the northern and 45 degs for the southern. They are usually thought to be ventilation-channels, but would be better be considered as open ways for the king's soul to reach the circumpolar stars to the North and the Orion constellation, to the South." ('A History of Egyptian Architecture', Badawy 1954: 138)"
from here: [
www.kolumbus.fi]
CT